The present invention is directed generally to the centrifugal treatment of liquids, and more particularly to apparatus for centrifugally treating liquid by separating it into fractions of different densities. The invention has particular application to the fractionation of whole blood and the present disclosure is directed primarily to this application. However, it will be understood that the apparatus of the present invention is applicable to the treatment of other liquids and semi-liquid masses as well.
Intervivos blood processing, wherein blood is taken from a live donor, passed through centrifugal processing apparatus, and then returned to the donor, has come into wide use during recent years. During passage through the centrifugal processing apparatus the blood is separated or fractionated into its component parts, i.e., plasma, red blood cells (RBC's), and white blood cells (WBC's) or platelets, and some portion of these fractions may be returned to the donor while other portions may be selectively retained within suitable storage means.
Apparatus for the intervivos processing of blood typically consists of a chamber of relatively small interior volume through which the whole blood from the donor is caused to flow while under the force of centrifugation. Because of their difference in densities the blood components congregate in zones of different radial distances from the center of rotation of the separation chamber. Collection ports in the chamber then remove the components for storage or recirculation.
The centrifugal processing chamber may be constructed in various forms, such as the bowl-shape contemplated in U.S. Pat. Nos. 3,489,145 and 3,655,123, or the annular diamond shaped cross-section form illustrated herein. In either case, the object is to provide a chamber wherein the red blood cell component, which has the highest specific gravity, can congregate during centrifugation at one radial extreme of the chamber, and the plasma component, which has the lowest specific gravity, can congregate at the other radial extreme of the chamber. Between these extremes a collection point is provided for the white blood cell component, which has a specific gravity between the red blood cell and plasma components.
One problem heretofore encountered with intervivos centrifugal liquid processing apparatus has been the necessity of having to accurately control flow rates and collection rates in the processing chamber so as to maintain the white blood cell component within the central portion of the chamber wherein it can be collected by the appropriate collection port. Typically, this has required that the process be continuously monitored, either by a technician or by a suitable electro-optical system, to assure that the separated components are being collected in their respective zones. Any failure in this respect can result in the collected components being rendered unusable.
The present invention is directed to a centrifugal liquid processing apparatus which is less critical to variations in flow rates and therefore provides more consistent collection of a desired fraction such as white blood cell components even under varying flow conditions.
Accordingly, it is a general object of the present invention to provide a new and improved centrifugal liquid processing apparatus.
It is another object of the present invention to provide a new and improved centrifugal liquid processing apparatus wherein a desired fractional component is derived with improved consistency.
It is another object of the present invention to provide a new and improved centrifugal liquid processing apparatus which is less susceptible to variations in flow rates.
It is another object of the present invention to provide new and improved apparatus for the intervivos separation of whole blood into its constituent components.